Evaluating manure on the farm

Dairy managers watch manure changes as a guide when making feed changes. Fresh, undisturbed piles of feces or droppings may provide valuable clues on the nutritional status of the cow. Four aspects of manure evaluation can be considered.

Washing a cup of manure through a screen (6 to 8 squares to the inch) allows the dairy manager, nutritionist, or veterinarian to quickly find or "see" if feed processing and digestion is optimal. Take a cup of fresh manure and wash it with a stream of warm water (cold water takes longer) through the screen removing the digested material. It typically takes about 30 seconds if your screen has sides allowing for more water pressure. Look for the following remaining feed particles.

- Finding pieces of barley or corn grain with white starch remaining indicates that some feed value was lost. If the seed and starch pieces are hard, additional grinding or processing may be needed to expose the starch to rumen microbial fermentation or lower gut enzymatic digestion.

-Corn kernels from corn silage reflect that the seed was too hard for digestion and chewing by the cow. Mature and dry corn silage can cause this observation as grain is hard. Some corn silage varieties can be selected for softer kernels allowing for more digestion.

- Whole cottonseeds or soybean splits (half of a soybean seed) that appear in the washed manure reflect a loss of feed nutrients. The seeds are not caught in the rumen mat which does not allows for chewing (cottonseed) or the soybean seeds are hard and must be processed finer. Wisconsin worker suggest breaking soybeans into fourths or eighths.

- Forage particles over ½ inch long may reflect a lack of long forage particles to maintain the rumen mat and adequate cud chewing. A high rate of passage reduces the time needed in the rumen to digest the forage properly.

Michigan workers developed a scoring system to evaluate fresh manure. Consistency is dependent on water and fiber content of the manure, type of feed, and passage rate. A scale of 1 to 5 is listed below with a score 3 optimal.

Score 1. This manure is very liquid with the consistency of pea soup. The manure may actually "arc" for the rump of the cow. Excess protein or starch, too much mineral, or lack of fiber can lead to this score. Excess urea in the hind gut can create an osmotic gradient drawing water in the manure. Cow with diarrhea will be in this category.

Score 2.This manure will appear runny and does not form a distinct pile. It will measure less than on inch in height and splatters when it hits the ground or concrete. Cows on lush pasture will commonly have this type of manure. Low fiber or a lack of functional fiber can also lead to this manure score.

Score 3. This is the optimal score! The manure has a porridge-like appearance, will stack up 1 ½ to 2 inches, have several concentric rings, a small depression or dimple in the middle, make a plopping sound with it hits concrete floors, and it will stick to the toe of your shoe.

Score 4. The manure is thicker, will stick to your shoe, and stacks up over 2 inches. Dry cows and older heifers may have this type of manure (this may reflect that low quality forages are fed and/or a shortage of protein). Adding more grain or protein can lower this manure score.

Score 5. This manure appears as firm fecal balls. Feed a straw based diet or dehydration would contribute to this score. Cows with a digestive blockage may exhibit this score.

Manure scores 1 and 5 are not desirable and may reflect a health problem besides dietary limitations. Score 4 droppings may reflect a need to rebalance the ration. As cows progress through their lactation, manure score may also shift as outlined below.

Fresh cows (score 2 to 2 ½)

Early lactation cows (2 ½ to 3)

Late lactation cows (3 to 3 ½)

Far off dry cows (3 to 4)

Close up dry cows (2 ½ to 3 ½)

Increasing the amount of degradable, soluble, or total protein; deceasing the amount or physical form of the fiber; increasing starch level, decreasing grain particle size (such as fine grinding or steam flaking), and consuming excess minerals (especially potassium and sodium) can cause manure scores to decline (for example from 3 to 2).

The color of manure is influenced by feed, amount of bile, and passage rate. Cows on pasture are dark green while hay based rations are more brown. High grain-based diets are more gray-like. Slower rates of passage causes the color to darken and become more ball-shaped with a shine on the surface due to mucus coating. Score 1 may be more pale due to more water and less bile content. Hemorrhage in the small intestine causes black and tar-like manure while bleeding in the rectum results in red to brown discoloration or streaks of red.

While manure evaluation is not scientifically or research based, it can be another tool to use on the farm. Once you become comfortable and skilled with the causes and results; you have earned your degree as a "manurologist".

Fecal starch can be conducted to evaluate if ration starch is being utilized by the dairy cow.   Cows may not use feed sources of starch due to physical form (not ground or processed correctly), rumen acidosis reducing microbial growth, and/or high rates of passage through the digestive tract.    Usually, the fecal starch cannot be seen when conducting a fecal washing.   If fecal starch is elevated, fecal pH may also be lowered due to fermentation in the large intestine.